Solar cells may be defined as devices for converting light energy into electric energy by using a photovoltaic effect of generating electrons when light is incident onto a P-N junction diode. The solar cell may be classified into a silicon solar cell, a compound semiconductor solar cell mainly including a group I-III-VI compound or a group III-V compound, a dye-sensitized solar cell, and an organic solar cell according to materials constituting the junction diode.
A solar cell made from CIGS (CuInGaSe), which is one of group I-III-VI Chal-copyrite-based compound semiconductors, represents superior light absorption, higher photoelectric conversion efficiency with a thin thickness, and superior electro-optic stability, so the CIGS solar cell is spotlighted as a substitute for a conventional silicon solar cell.
Referring to FIG. 1, a general CIGS thin film solar cell is fabricated by sequentially forming a substrate 10 including sodium (Na), a back electrode layer 20, a light absorbing layer 30, a buffer layer 40, a high-resistance buffer layer 50, and a front electrode layer 60. Different from a bulk solar cell, the CIGS thin film solar cell is defined by a plurality of solar cell units connect to each other in series or parallel through patterning processes P1 to P3. Inactive regions G1 and G2 are inevitably generated during the patterning processes P1 to P3, thereby lowering the light output of the solar cell module.
Among them, the P3 patterning process is performed to separate a plurality of solar cells C1, C2, and C3. According to the related art, the layers are mechanically removed using a scribing tip (needle). However, such a scheme has a difficulty in controlling a line-width due to the layer tearing so that accurate pattering is difficult. In addition, a suction device or washing device for separating residual materials generated during processing is necessary.